    .donghua {
        width: 150px;
        height: 300px;
        margin: 0 auto;
        overflow: hidden;
        background-image: url(../img/dongtu.webp);
        animation: donghua step-end 1s infinite;
    }
    
    @keyframes donghua {
        0% {
            /* margin-left:0px; */
            background-position: 0px 0px;
        }
        25% {
            background-position: -150px 0px;
        }
        50% {
            background-position: -300px 0px
        }
        75% {
            background-position: -450px 0px
        }
        100% {
            background-position: -600px 0px
        }
    }
    
    .bigdonghua {
        width: 100%;
        height: 400px;
        z-index: 1000;
        position: relative;
        margin-top: 100px;
    }
    
    .bigdonghua-center {
        width: 800px;
        height: 200px;
        margin: 0 auto;
        display: flex;
    }